Patent Literature 1 discloses a two-dimensional photonic crystal surface emitting laser. In this two-dimensional photonic crystal surface emitting laser, a photonic crystal periodic structure 21 including a second medium with a different refractive index is arranged in a two-dimensional period in an active layer 12 (a first medium) that emits light due to injection of carriers or near the active layer 12. A lattice structure of a photonic crystal 20 is a square lattice or an orthogonal lattice and has a translational symmetry, but does not have a rotational symmetry. Alternatively, the lattice structure of the photonic crystal 20 is a square lattice or an orthogonal lattice, and is any one of pl, pm, pg or cm in a two-dimensional pattern classification method. A shape of a lattice point may be approximately a triangle.